Chocolate sponge cake that's light, airy and bakes up level for any chocolate layer cake. Step-by-step photos and tips for a tall, moist sponge.
- 4 large eggs Room temperature
- ⅛ tsp kosher salt Morton
- ¾ cup granulated sugar
- 2 Tbsp unsalted butter Melted and cooled to warm (Note 1)
- ¾ cup all-purpose flour 1 cup = 150 g (Note 2)
- ¼ cup unsweetened cocoa powder Natural or Dutch-process
- 1½ tsp baking powder (Note 3)
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Prep the pan. Heat the oven to 350°F (175°C) with a rack in the center. Line the bottom of an 8-inch round cake pan, at least 2 inches tall, with parchment. Leave the sides bare. Wrap soaked, squeezed-out cake strips around the outside of the pan (Note 4, Note 5).
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Mix the dry ingredients. Sift ¾ cup all-purpose flour, ¼ cup unsweetened cocoa powder and 1½ tsp baking powder together and set aside.
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Melt the butter. Melt 2 Tbsp unsalted butter and let it cool to warm, about 100°F (38°C).
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Whip the eggs. In a stand mixer fitted with the whip attachment, whip 4 large eggs and ⅛ tsp kosher salt on high until foamy. Add ¾ cup granulated sugar a spoonful at a time, then keep whipping until pale, thick and tripled, about 15 minutes. It should fall from the whip in a ribbon that holds for about 3 seconds. Don't stop early.
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Fold in the dry mix. Add the dry ingredients in two halves, folding gently with a wide spatula just until no streaks are left. Don't overmix.
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Fold in the butter. Pour the warm butter down the side of the bowl and fold just until blended.
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Pour the batter. Pour it into the prepared pan and swirl the pan back and forth a couple of times to level it.
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Bake at 350°F (175°C). Bake on the middle rack until the top springs back when pressed, OR until a toothpick in the center comes out clean. Mine takes about 25 minutes. Keep the door shut for the first 15 minutes, and close it gently when you check.
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Cool and release. Cool in the pan for 5 minutes. Run a thin knife around the edge, turn the cake out onto a cooling rack, peel off the parchment and let it cool completely.
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Split the layers. Rest one hand flat on top of the cooled cake. Score all the way around the side, halfway up and about ½ inch deep, turning the cake as you go. Keep turning and cutting deeper until the two layers come apart. A cake slicer or leveling clips keep the cut even.
1. Butter: cool the melted butter to warm, about 100°F (38°C), like warm bath water. Hot butter knocks the air out of the whipped eggs.
2. Measuring flour: 1 cup = 150 g. Weigh it if you have a scale.
3. Scaling the baking powder: changing the servings multiplies every amount straight across. Keep the first batch of baking powder in full and add only ¾ of it for each extra batch, so 1½ tsp becomes 2⅝ tsp when you double the recipe, not 3 tsp.
4. Cake strips: soak cake strips in water, squeeze them out and wrap them around the outside of the pan. They keep the edges from baking faster than the middle, so the top bakes flat. No strips? Pin a damp strip of kitchen towel around the pan, or trim the dome with a serrated knife.
5. Pans: one 8x2-inch pan gives a 2-inch cake to split into two layers. Two 8-inch pans give two 1-inch layers with no splitting; bake them at the same time and start checking early. For a taller cake, double the recipe in an 8x3-inch pan, about ¾ full. It bakes a little denser than two pans.
6. Make ahead: bake the sponge a day or two before you build your cake, wrapped tightly at room temperature.
7. Storage: wrapped, the plain sponge keeps 2 days at room temperature or up to 1 month in the freezer. Thaw it in its wrap.